Exhaust system temperature estimation systems and methods

ABSTRACT

A control system for an engine of a vehicle includes an adder module that determines a temperature sum based on a sum of a plurality of temperatures determined based on (i) a plurality of operating parameters of the vehicle and (ii) a plurality of predetermined values calibrated for determining an estimated temperature at a location within an exhaust system of the vehicle. A temperature difference module determines a temperature difference based on the temperature sum and a previous value of the temperature difference. An estimating module determines the estimated temperature at the location within the exhaust system based on the temperature difference and a reference temperature. An actuator control module selectively adjusts at least one engine actuator based on the estimated temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.14/873,583 filed on Oct. 2, 2015. The disclosure of the aboveapplication is incorporated herein by reference in its entirety.

FIELD

The present disclosure relates to internal combustion engine systems andmore particularly to systems and methods for estimating temperaturewithin an exhaust system of a vehicle.

BACKGROUND

The background description provided here is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this background section, aswell as aspects of the description that may not otherwise qualify asprior art at the time of filing, are neither expressly nor impliedlyadmitted as prior art against the present disclosure.

An engine combusts a mixture of air and fuel to produce drive torque andpropel a vehicle. Air is drawn into the engine through a throttle valve.Fuel provided by one or more fuel injectors mixes with the air to formthe air/fuel mixture. The air/fuel mixture is combusted within one ormore cylinders to produce drive torque. An engine control module (ECM)controls the torque output of the engine.

Exhaust gas resulting from combustion of the air/fuel mixture isexpelled from the engine to an exhaust system. The ECM may adjust one ormore engine parameters based on signals from various sensors that arelocated in the exhaust system. For example only, one or more temperaturesensors and/or exhaust flow rate sensors may be located in the exhaustsystem. The ECM may adjust, for example, airflow into the engine, theamount of fuel injected, and/or spark timing based on the signals.

The sensors provide the ECM with measurements regarding conditionswithin the exhaust system and allow the ECM to adjust one or more engineparameters to create desired exhaust conditions. As the number ofsensors implemented in the exhaust system increases, however, the costof producing the vehicle also increases. The increased production costmay be attributable to, for example, the sensors themselves, associatedwiring and hardware, and/or research and development. Additionally, avehicle producer may produce a variety of different vehicles, and eachof the different vehicles may have a different exhaust system.Calibrating and adjusting sensors implemented in each different vehicleand exhaust system may also increase vehicle production cost.

SUMMARY

In a feature, a control system for an engine of a vehicle is described.An adder module determines a temperature sum based on a sum of aplurality of temperatures determined based on (i) a plurality ofoperating parameters of the vehicle and (ii) a plurality ofpredetermined values calibrated for determining an estimated temperatureat a location within an exhaust system of the vehicle. A temperaturedifference module determines a temperature difference based on thetemperature sum and a previous value of the temperature difference. Anestimating module determines the estimated temperature at the locationwithin the exhaust system based on the temperature difference and areference temperature. An actuator control module selectively adjusts atleast one engine actuator based on the estimated temperature.

In further features, a first change module determines a firsttemperature change based on a difference between the temperature sum andthe previous value of the temperature difference, and a second changemodule determines a second temperature change based on a product of thefirst temperature change and a gain value. The temperature differencemodule sets the temperature difference based on a sum of the previousvalue of the temperature difference and the second temperature change.

In further features, a gain module determines the gain value based on anengine coolant temperature.

In further features, the estimating module determines the estimatedtemperature at the location within the exhaust system based on a sum ofthe temperature difference and the reference temperature.

In further features, the plurality of operating parameters include atleast two of: (i) a vehicle speed; (ii) a radiator fan speed; (iii) anengine speed; (iv) a manifold pressure; (v) an engine coolanttemperature; (vi) a difference between the engine coolant temperatureand an ambient air temperature; (vii) a spark timing of the engine;(viii) a mass air flowrate into the engine; (ix) a mass fuel flowrate tothe engine; (x) a wastegate opening; (xi) a present air/fuel ratio ofthe engine; (xii) an intake air temperature; and (xiii) the ambient airtemperature.

In further features, the plurality of operating parameters include: (i)a vehicle speed; (ii) a radiator fan speed; (iii) an engine speed; (iv)a manifold pressure; (v) an engine coolant temperature; (vi) adifference between the engine coolant temperature and an ambient airtemperature; (vii) a spark timing of the engine; (viii) a mass airflowrate into the engine; (ix) a mass fuel flowrate to the engine; (x) awastegate opening; (xi) a present air/fuel ratio of the engine; (xii) anintake air temperature; and (xiii) the ambient air temperature.

In further features, the plurality of operating conditions do notinclude any temperature measured in the exhaust system using atemperature sensor.

In further features, the plurality of operating conditions do notinclude any pressure measured in the exhaust system using a pressuresensor.

In further features: a second adder module determines a secondtemperature sum based on a sum of a second plurality of temperaturesdetermined based on (i) the plurality of operating parameters of thevehicle and (ii) a second plurality of predetermined values calibratedfor determining a second estimated temperature at a second locationwithin the exhaust system of the vehicle; a second temperaturedifference module determines a second temperature difference based onthe second temperature sum and a previous value of the secondtemperature difference; and a second estimating module determines thesecond estimated temperature at the second location within the exhaustsystem of the vehicle based on the second temperature difference and thereference temperature. The actuator control module further selectivelyadjusts at least one engine actuator based on the second estimatedtemperature.

In further features, based on the estimated temperature, the actuatorcontrol module selectively adjusts at least one of opening of a throttlevalve, fueling of the engine, spark timing of the engine, cam phasing ofthe engine, opening of an exhaust gas recirculation (EGR) valve, andopening of a wastegate.

In a feature, a control method for an engine of a vehicle includes:determining a temperature sum based on a sum of a plurality oftemperatures determined based on (i) a plurality of operating parametersof the vehicle and (ii) a plurality of predetermined values calibratedfor determining an estimated temperature at a location within an exhaustsystem of the vehicle; determining a temperature difference based on thetemperature sum and a previous value of the temperature difference;determining the estimated temperature at the location within the exhaustsystem based on the temperature difference and a reference temperature;and selectively adjusting at least one engine actuator based on theestimated temperature.

In further features, the control method further includes: determining afirst temperature change based on a difference between the temperaturesum and the previous value of the temperature difference; anddetermining a second temperature change based on a product of the firsttemperature change and a gain value, wherein determining the temperaturedifference includes setting the temperature difference based on a sum ofthe previous value of the temperature difference and the secondtemperature change.

In further features, the control method further includes determining thegain value based on an engine coolant temperature.

In further features, determining the estimated temperature includesdetermining the estimated temperature at the location within the exhaustsystem based on a sum of the temperature difference and the referencetemperature.

In further features, the plurality of operating parameters include atleast two of: (i) a vehicle speed; (ii) a radiator fan speed; (iii) anengine speed; (iv) a manifold pressure; (v) an engine coolanttemperature; (vi) a difference between the engine coolant temperatureand an ambient air temperature; (vii) a spark timing of the engine;(viii) a mass air flowrate into the engine; (ix) a mass fuel flowrate tothe engine; (x) a wastegate opening; (xi) a present air/fuel ratio ofthe engine; (xii) an intake air temperature; and (xiii) the ambient airtemperature.

In further features, the plurality of operating parameters include: (i)a vehicle speed; (ii) a radiator fan speed; (iii) an engine speed; (iv)a manifold pressure; (v) an engine coolant temperature; (vi) adifference between the engine coolant temperature and an ambient airtemperature; (vii) a spark timing of the engine; (viii) a mass airflowrate into the engine; (ix) a mass fuel flowrate to the engine; (x) awastegate opening; (xi) a present air/fuel ratio of the engine; (xii) anintake air temperature; and (xiii) the ambient air temperature.

In further features, the plurality of operating conditions do notinclude any temperature measured in the exhaust system using atemperature sensor.

In further features, the plurality of operating conditions do notinclude any pressure measured in the exhaust system using a pressuresensor.

In further features, the control method further includes: determining asecond temperature sum based on a sum of a second plurality oftemperatures determined based on (i) the plurality of operatingparameters of the vehicle and (ii) a second plurality of predeterminedvalues calibrated for determining a second estimated temperature at asecond location within the exhaust system of the vehicle; determining asecond temperature difference based on the second temperature sum and aprevious value of the second temperature difference; determining thesecond estimated temperature at the second location within the exhaustsystem of the vehicle based on the second temperature difference and thereference temperature; and selectively adjusting at least one engineactuator based on the second estimated temperature.

In further features, adjusting at least one engine actuator includesadjusting at least one of opening of a throttle valve, fueling of theengine, spark timing of the engine, cam phasing of the engine, openingof an exhaust gas recirculation (EGR) valve, and opening of a wastegate.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims and the drawings. Thedetailed description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an example engine system;

FIG. 2 is a functional block diagram of an example exhaust system;

FIG. 3 is a functional block diagram of an example engine controlsystem;

FIG. 4 is a functional block diagram of an example temperatureestimation system;

FIG. 5 is a functional block diagram of an example temperatureestimation module;

FIG. 6 is a functional block diagram of an example temperatureestimation system; and

FIG. 7 is a flowchart depicting an example method of determining anestimated temperature within an exhaust system.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION

An exhaust system of a vehicle includes exhaust system componentsthrough which exhaust flows before the exhaust is expelled toatmosphere. Temperature and/or pressure sensors could be implemented tomeasure temperatures and/or pressures at various locations within theexhaust system. Temperature and pressure sensors, however, increasevehicle cost.

An estimation module according to the present application determines oneor more estimated temperatures at one or more locations, respectively,within the exhaust system. The estimation module determines an estimatedtemperature at one location based on a sum of a plurality of temperaturecontributions determined based on (i) a plurality of operatingparameters and (ii) a plurality of predetermined values calibrated fordetermining the estimated temperature.

The estimation module may also determine a second estimated temperatureat a second location based on the same plurality of input parameters andsecond predetermined values calibrated for determining the secondestimated temperature. The use of the same input parameters andtemperature estimation strategy minimizes complexity and simplifiescalibration as only the predetermined values would be calibrated inorder to estimate different temperatures. Temperature and pressuresensors can also be omitted from the exhaust system, thereby minimizingthe associated vehicle cost.

Referring now to FIG. 1, a functional block diagram of an engine system100 is presented. An air/fuel mixture is combusted within an engine 102to produce drive torque for a vehicle. The engine 102 may be agasoline-type engine, a diesel-type engine, a hybrid-type engine, and/oranother suitable type of engine. The engine 102 may be configured in anysuitable configuration. For example only, the engine 102 may beconfigured in a V-type configuration, a flat-type configuration, or aninline-type configuration.

Air is drawn into the engine 102 through an intake manifold 104 and athrottle valve 106. The throttle valve 106 is actuated to controlairflow into the engine 102. A throttle actuator module 108, such as anelectronic throttle controller, controls the throttle valve 106 and,therefore, airflow into the engine 102.

A fuel system 110 injects fuel that mixes with the air to form theair/fuel mixture. The fuel system 110 may provide fuel into the intakemanifold 104, into intake valves (not shown) associated with cylinders112 of the engine 102, and/or directly into each of the cylinders 112.In various implementations, the fuel system 110 includes one fuelinjector (not shown) for each of the cylinders 112.

The air/fuel mixture is combusted within the cylinders 112 of the engine102. Combustion of the air/fuel mixture may be initiated by, forexample, spark provided by spark plugs 114. In some engine systems, suchas the engine system 100, one spark plug may be provided for each of thecylinders 112. In other engine systems, such as diesel-type enginesystems, combustion may be accomplished without the spark plugs 114.Combustion of the air/fuel mixture generates drive torque and rotatablydrives a crankshaft (not shown).

The engine 102 may include eight cylinders as shown in FIG. 1, althoughthe engine 102 may include a greater or fewer number of cylinders. Thecylinders 112 of the engine 102 are depicted as being arranged in twocylinder banks: a left cylinder bank 116 and a right cylinder bank 118.While the engine 102 is shown as including the left and right cylinderbanks 116 and 118, the engine 102 may include one cylinder bank or morethan two cylinder banks. Inline-type engines may be considered to havecylinders arranged in one cylinder bank.

An engine control module (ECM) 150 controls the torque output of theengine 102. The ECM 150 may control the torque output of the engine 102based on driver inputs provided by a driver input module 152. Forexample only, the driver inputs may include an accelerator pedalposition, brake pedal position, cruise control input, and/or one or moreother driver inputs.

The ECM 150 may communicate with a hybrid control module 154 tocoordinate operation of the engine 102 and one or more electric motors,such as electric motor (EM) 156. The EM 156 may also function as agenerator, and may be used to selectively produce electrical energy foruse by vehicle electrical systems and/or for storage in a battery.

The ECM 150 makes control decisions based on parameters measured byvarious sensors. For example, intake air temperature may be measuredusing an intake air temperature (IAT) sensor 158. Ambient airtemperature may be measured using a ambient temperature sensor 160. Massflow rate of air into the engine 102 may be measured using a massairflow (MAF) sensor 162. Pressure within the intake manifold 104 may bemeasured using a manifold absolute pressure (MAP) sensor 164. In variousimplementations, engine vacuum may be measured, where engine vacuum isdetermined based on the difference between ambient air pressure and thepressure within the intake manifold 104.

Engine coolant temperature (ECT) may be measured using a coolanttemperature sensor 166. The coolant temperature sensor 166 may belocated within the engine 102 or at other locations where the coolant iscirculated, such as a radiator (not shown). Engine speed may be measuredusing an engine speed sensor 168. For example only, the engine speed maybe measured based on the rotational speed of the crankshaft. Vehiclespeed may be measured using a vehicle speed sensor 169. For example, thevehicle speed may be measured using one or more wheel speed sensors. Oneor more other sensors 167 may also be provided.

The ECM 150 includes an actuator control module 170 that controls engineoperating parameters. For example only, the actuator control module 170may adjust throttle opening, amount and/or timing of fuel injection,spark timing, cylinder deactivation, and/or turbocharger boost. Theactuator control module 170 may also control other engine parameters,such as exhaust gas recirculation (EGR) valve opening, lift of intakeand/or exhaust valves, and/or phasing of intake and/or exhaust valves.

Referring now to FIG. 2, a functional block diagram of an exampleexhaust system 200 is presented. The exhaust system 200 includes exhaustsystem components through which exhaust gas flows. While the exhaustsystem 200 is provided as an example, the present disclosure is alsoapplicable to other exhaust system configurations including exhaustsystems having different components and/or different arrangements ofcomponents.

Exhaust gas resulting from combustion of the air/fuel mixture isexpelled from the engine 102 to the exhaust system 200. In the exampleof FIG. 2, exhaust is expelled from the cylinders 112 of the rightcylinder bank 118 to a right exhaust manifold 202. Exhaust is expelledfrom the cylinders 112 of the left cylinder bank 116 to a left exhaustmanifold 204. Exhaust expelled from cylinders arranged in one cylinderbank may be output to one exhaust manifold.

With respect to the left exhaust manifold 204, the exhaust may flow fromthe left exhaust manifold 204 past a first wastegate 206 and a secondwastegate 208. The first and second wastegates 206 and 208 areassociated with first and second turbochargers 210 and 212,respectively. In various implementations, one turbocharger and wastegatemay be implemented.

The turbochargers 210 and 212 provide pressurized air to the engine 102,such as upstream of the throttle valve 106. The turbochargers 210 and212 are driven by exhaust flow through the turbochargers 210 and 122.One or more intercoolers (not shown) may also be implemented todissipate heat from the pressurized air. The temperature of thepressurized air may be increased by, for example, the pressurization ofthe air and/or via exhaust heat.

The wastegates 206 and 208 may allow the exhaust gas to bypass theturbochargers 210 and 212, respectively. In this manner, the wastegates206 and 208 may be used to control the output (i.e., boost) of theturbochargers 210 and 212, respectively.

A boost actuator module 214 controls opening of the wastegates 206 and208, and therefore output of the turbochargers 210 and 212, based onsignals from the actuator control module 170. The boost actuator module214 may control the positions of the wastegates 206 and 208 bycontrolling the duty cycle (DC) of power applied to the wastegates 206and 208.

The exhaust from the left cylinder bank 116 may flow from the wastegates206 and 208, to a first catalyst 218. The first catalyst 218 may includeany suitable type of catalyst. For example only, the first catalyst 218may include a diesel oxidation catalyst (DOC), a selective catalystreductant (SCR) catalyst, a catalytic converter (e.g., three-waycatalyst or a four-way catalyst), and/or any other exhaust catalyst. Thefirst catalyst 218 may include one or more individual catalyst bricks.

The exhaust from the left cylinder bank 116 may flow from the firstcatalyst 218 to a first muffler 232. The first muffler 232 dampensacoustic noise produced by the cylinders 112 of the left cylinder bank116.

The exhaust from the cylinders 112 of the right cylinder bank 118 flowfrom the right exhaust manifold 202 to a second catalyst 264. The secondcatalyst 264 may include any suitable type of catalyst. For exampleonly, the second catalyst 264 may include a diesel oxidation catalyst(DOC), a selective catalyst reductant (SCR) catalyst, a catalyticconverter (e.g., three-way catalyst or a four-way catalyst), and/or anyother exhaust catalyst. The second catalyst 264 may include one or moreindividual catalyst bricks.

The exhaust from the right cylinder bank 118 may flow from the secondcatalyst 264 to a second muffler 268. The first muffler 268 dampensacoustic noise produced by the cylinders 112 of the right cylinder bank118. In various implementations, the two exhaust streams may be joined,such as by a Y-pipe, an X-pipe, or an H-pipe. While both of theturbochargers are shown and described as being associated with theexhaust from the left cylinder bank 116, one turbocharger may beassociated with each cylinder bank in various implementations.

An exhaust gas recirculation (EGR) system 280 may be associated with theleft exhaust manifold 204 and/or the right exhaust manifold 202. Forexample only, the EGR system 280 may be associated with the rightexhaust manifold 202, as shown in FIG. 2. An EGR valve 282 receivesexhaust gas from the right exhaust manifold 202. When open, the EGRvalve 282 redirects exhaust gas from the right exhaust manifold 202 backto the intake manifold 104. The actuator control module 170 controlsactuation of the EGR valve 282 and, therefore, exhaust gas recirculationback to the engine 102. An EGR cooler (not shown) may also beimplemented to cool recirculated exhaust gas before the recirculatedexhaust gas is mixed with intake air. As stated above, the exhaustsystem 200 of FIG. 2 is provided as an example only, and the presentdisclosure is also applicable to exhaust systems having differentcomponents and/or different arrangements of components.

The ECM 150 includes an estimation module 290 that estimates one or moreexhaust system temperatures. While the estimation module 290 and theactuator control module 170 are shown and discussed as being locatedwithin the ECM 150, the estimation module 290 and/or the actuatorcontrol module 170 may be located in any suitable location, such asexternal to the ECM 150. The estimation module 290 estimates the exhaustsystem temperature(s) using the same input parameters and model withpredetermined values calibrated for the estimating each respectiveexhaust system temperature.

The actuator control module 170 selectively adjusts one or more engineoperating parameters based on the one or more of the estimated exhaustsystem temperatures. In this manner, the actuator control module 170 mayuse one or more of the estimated exhaust system temperatures to createtarget exhaust system conditions. One or more of the estimated exhaustsystem temperatures may be used for one or more other reasons, such asfault diagnostics and other suitable uses.

Referring now to FIG. 3, a functional block diagram of an exampleimplementation of the actuator control module 170 is presented. A torquerequest module 304 determines a torque request 308 for the engine 102based on one or more driver inputs 312. The driver inputs 312 mayinclude, for example, an accelerator pedal position, a brake pedalposition, a cruise control input, and/or one or more other suitabledriver inputs. The torque request module 304 may determine the torquerequest 308 additionally or alternatively based on one or more othertorque requests, such as torque requests generated by the ECM 150 and/ortorque requests received from other modules of the vehicle, such as atransmission control module, the hybrid control module 154, a chassiscontrol module, etc.

One or more engine actuators are controlled based on the torque request308 and/or one or more other parameters. For example, a throttle controlmodule 316 may determine a target throttle opening 320 based on thetorque request 308. The throttle actuator module 108 may adjust openingof the throttle valve 106 based on the target throttle opening 320.

Generally speaking, a spark control module 324 determines a target sparktiming 328 based on the torque request 308. The spark control module 324generates spark based on the target spark timing 328. A fuel controlmodule 332 determines one or more target fueling parameters 336 based onthe torque request 308. For example, the target fueling parameters 336may include fuel injection amount, number of fuel injections forinjecting the amount, and injection timing. The fuel system 110 injectsfuel based on the target fueling parameters 336.

A phaser control module 337 determines target intake and exhaust camphaser angles 338 and 339 based on the torque request 308. A phaseractuator module may regulate intake and exhaust cam phasers (not shown)based on the target intake and exhaust cam phaser angles 338 and 339,respectively. A boost control module 340 may determine one or moretarget wastegate DCs, such as target wastegate DC 342, based on thetorque request 308. The boost actuator module 214 may control awastegate based on the target wastegate DC 342. A cylinder controlmodule 344 generates a cylinder activation/deactivation command 348based on the torque request 308.

A cylinder actuator module (not shown) deactivates the intake andexhaust valves of cylinders that are to be deactivated based on thecylinder activation/deactivation command 348. The cylinder actuatormodule allows opening and closing of the intake and exhaust valves ofcylinders that are to be activated based on the activation/deactivationcommand 348. The fuel control module 332 halts fueling of cylinders thatare to be deactivated.

Referring now to FIG. 4, a functional block diagram of an exampleimplementation of the estimation module 290 is shown. The estimationmodule 290 includes a temperature estimation module 404 that determinesan estimated temperature 408 at a location of an exhaust system. Theestimated temperature 408 may be a temperature of an exhaust systemcomponent (e.g., metal or a catalyst) at the location or a temperatureof exhaust gas at the location. Examples of the estimated temperature408 include, but are not limited to, an estimated exhaust manifoldtemperature, an estimated exhaust temperature at an inlet of an exhaustcatalyst, an estimated exhaust temperature at an outlet of a catalyst,an estimated temperature of a front portion of a catalyst, an estimatedtemperature of a rear portion of a catalyst, and an estimatedtemperature of a middle portion of a catalyst.

Sources of heat to the exhaust system include combustion within theengine, the engine block itself, and one or more exhaust catalyst(s).The temperature estimation module 404 determines the estimatedtemperature 408 based on a plurality of input parameters 412 andpredetermined values 416 for determining the estimated temperature 408.The predetermined values 416 are calibrated for determining theestimated temperature 408 for possible combinations of the inputparameters 412.

The input parameters 412 include engine coolant temperature (ECT) 420,ambient (air) temperature 424, intake air temperature (IAT) 428, vehiclespeed (VS) 432, a radiator fan speed 436, and an engine speed (RPM) 440.The input parameters 412 also include a manifold pressure (e.g., MAP)444, a spark timing 448, a mass air flowrate (MAF) 452 into the engine,a mass fuel (injection) flowrate (MFF) 456, a wastegate (WG) opening460, and an air/fuel ratio 464 being supplied to the engine. In variousimplementations, the input parameters 412 do not include any measuredtemperatures within the exhaust system and/or do not include anymeasured pressures within the exhaust system.

The ECT 420 may be measured by an ECT sensor (e.g., the coolanttemperature sensor 166), and the ambient temperature 424 may be measuredby an ambient temperature sensor (e.g., the ambient temperature sensor160). The IAT 428 may be measured using an IAT sensor (e.g., the IATsensor 158), and the VS 432 may be measured using one or more sensors(e.g., the vehicle speed sensor 169). The radiator fan speed 436 mayindicate whether a radiator fan is commanded on or off or, in the caseof a variable speed radiator fan, indicate a commanded speed setting ofthe radiator fan. The RPM 440 may be measured using an engine speedsensor (e.g., the engine speed sensor 168), and the manifold pressure444 may be measured using a manifold pressure sensor (e.g., the MAPsensor 164). The spark timing 448 may be, for example, the target sparktiming 328. The MAF 452 may be measured using a MAF sensor (e.g., theMAF sensor 162), and the MFF 456 may be a target MFF provided by thefuel control module 332. The WG opening 460 may be, for example, thetarget WG DC 342. The air/fuel ratio 464 may be a target air/fuel ratio(e.g., a target equivalence ratio or EQR) for the engine.

Referring now to FIG. 5, a functional block diagram of an exampleimplementation of the temperature estimation module 404 is presented.Generally speaking, the temperature estimation module 404 includes aplurality of modules that determine respective temperaturecontributions. The temperature contributions can be positive in the caseof heat sources or negative in the case of heat sinks. The temperatureestimation module 404 determines the estimated temperature 408 based onthe temperature contributions, as discussed further below.

The temperature estimation module 404 may determine the estimatedtemperature 408 at a given time (n) based on the following equations:{tilde over (T)} _(e)(n)={tilde over (T)} _(e)(n−1)+α(ECT)[u(n)−{tildeover (T)} _(e)(n−1)],u(n)=g _(c)(VS(n),F(n),RPM(n),MAP(n),E{tilde over (C)}T(n))E{tilde over(C)}T(n)+g _(a)(RPM(n),MAP(n),S(n),E{tilde over (C)}T(n))MAF(n)+g_(f)(RPM(n))MFF(n)+g _(e)(RPM(n),WG(n))f _(e)(MAP(n),E{tilde over(C)}T(n))+g _(s)(MAP(n),E{tilde over (C)}T(n))S(n)+g _(ø)(MAP(n),E{tildeover (C)}T(n))ø(n)g _(r)(ECT(n),T _(amb)(n),IAT(n)),E{tilde over (C)}T(n)=ECT(n)−T _(amb)(n), andT _(e)(n)={tilde over (T)} _(e)(n)+T _(amb)(n)T_(e) is the estimated temperature 408, {tilde over (T)}_(e) correspondsto how much warmer the estimated temperature 408 is than the ambienttemperature T_(amb) 424, ECT is the ECT 420, E{tilde over (C)}Tcorresponds to a temperature difference between the ECT 420 and theambient temperature T_(amb) 424, IAT is the IAT 428, VS is the VS 432, Fis the radiator fan speed 436, and MAF is the MAF 452. MFF is the MFF456, RPM is the RPM 440, MAP is the manifold pressure 444, S is thespark timing 448, ø is the air/fuel ratio 464, and WG is the WG opening460. α(•), g_(c)(•), g_(a)(•), g_(f)(•), g_(e)(•), f_(e)(•), g_(s)(•),g_(ø)(•), and g_(r)(•) denote functions using the predetermined values416, and n is the time.

The term g_(c)(•)E{tilde over (C)} (n) corresponds to a heatcontribution from the engine block through heat transfer. The terms,g_(a)(•)MAF(n), g_(f)(•)MFF(n), and g_(e)(•)f_(e)(n), correspond to theheat contributions from air, fuel and exhaust flows, respectively. Theterm g_(s)(•)S(n) corresponds to the combustion phasing impact, and theterm g_(r)(•) represents a radiation heat sink. The term α(•) reflectsdynamic characteristics and is related to the system's time constant. Asdiscussed further below, the term α(•) is a function of the ECT 420.

A first component module 504 and a first multiplier module 508 generatea first temperature contribution 512 (e.g., in degrees K, C, or F) basedon the VS 432, the radiator fan speed 436, the RPM 440, the MAP 444, anda temperature difference 516 between the ECT 420 and the ambienttemperature 424. The first component module 504 generates a firsttemperature 520 as a function of the VS 432, the radiator fan speed 436,the RPM 440, the MAP 444, and the temperature difference 516 between theECT 420 and the ambient temperature 424. The function may be, forexample, a mapping or an equation including one or more of thepredetermined values 416 that relates VS, radiator fan speeds, RPMs,MAPs, and temperature differences to first temperatures. The firstmultiplier module 508 multiplies the first temperature 520 with thetemperature difference 516 to produce the first temperature contribution512. The first temperature contribution 512 corresponds to heating(i.e., temperature increase relative to the ambient temperature 424)provided by the engine via heat transfer (e.g., conduction).

A second component module 524 and a second multiplier module 528generate a second temperature contribution 532 (e.g., in degrees K, C,or F) based on the temperature difference 516 between the ECT 420 andthe ambient temperature 424, the RPM 440, the MAP 444, the spark timing448, and the MAF 452. The second component module 524 generates a secondvalue 536 as a function of the temperature difference 516 between theECT 420 and the ambient temperature 424, the RPM 440, the MAP 444, thespark timing 448. The function may be, for example, a mapping or anequation including one or more of the predetermined values 416 thatrelates temperature differences, RPMs MAPs, and spark timings to secondvalues. The second multiplier module 528 multiplies the second value 536with the MAF 452 to produce the second temperature contribution 532. Thesecond temperature contribution 532 corresponds to heating (i.e.,temperature increase relative to the ambient temperature 424) from airflow.

A third component module 540 and a third multiplier module 544 generatea third temperature contribution 548 (e.g., in degrees K, C, or F) basedon the RPM 440 and the MFF 456. The third component module 540 generatesa third value 552 as a function of the RPM 440. The function may be, forexample, a mapping or an equation including one or more of thepredetermined values 416 that relates RPMs to third values. The thirdmultiplier module 544 multiplies the third value 552 with the MFF 456 toproduce the third temperature contribution 548. The third temperaturecontribution 548 corresponds to heating (i.e., temperature increaserelative to the ambient temperature 424) from fuel flow.

A fourth component module 556, a fifth component module 560, and afourth multiplier module 564 generate a fourth temperature contribution568 (e.g., in degrees K, C, or F) based on the RPM 440, the WG opening460, the ECT 420, and the MAP 444. The fourth component module 556generates a fourth value 572 as a function of the RPM 440 and the WGopening 460. The function may be, for example, a mapping or an equationincluding one or more of the predetermined values 416 that relates RPMsand WG openings to fourth values. The fifth component module 560generates a fifth value 576 as a function of the ECT 420 and the MAP444. The function may be, for example, a mapping or an equationincluding one or more of the predetermined values 416 that relates ECTsand MAPs to fifth values. The fourth multiplier module 564 multipliesthe fourth value 572 with the fifth value 576 to produce the fourthtemperature contribution 568. The fourth temperature contribution 568corresponds to heating (i.e., temperature increase relative to theambient temperature 424) from exhaust flow.

A sixth component module 580 and a fifth multiplier module 584 generatea fifth temperature contribution 588 (e.g., in degrees K, C, or F) basedon the MAP 444, the temperature difference 516 between the ECT 420 andthe ambient temperature 424, and the spark timing 448. The sixthcomponent module 580 generates a sixth value 592 as a function of theMAP 444 and the temperature difference 516 between the ECT 420 and theambient temperature 424. The function may be, for example, a mapping oran equation including one or more of the predetermined values 416 thatrelates MAPs and temperature differences to sixth values. The fifthmultiplier module 584 multiplies the sixth value 592 with the sparktiming 448 to produce the fifth temperature contribution 588. The sparktiming 448 may be, for example, a value between 0.0 and 1.0 that is setbased on the target spark timing 328 relative to a predetermined optimalspark timing for the present operating conditions. The fifth temperaturecontribution 588 corresponds to a combustion phasing (e.g., spark timingadvance or retard) impact (i.e., temperature increase or decrease) onthe estimated temperature 408.

A seventh component module 596 and a sixth multiplier module 600generate a sixth temperature contribution 604 (e.g., in degrees K, C, orF) based on the MAP 444, the temperature difference 516 between the ECT420 and the ambient temperature 424, and the air/fuel ratio 464 beingsupplied to the engine. The seventh component module 596 generates aseventh value 608 as a function of the MAP 444 and the temperaturedifference 516 between the ECT 420 and the ambient temperature 424. Thefunction may be, for example, a mapping or an equation including one ormore of the predetermined values 416 that relates MAPs and temperaturedifferences to seventh values. The sixth multiplier module 600multiplies the seventh value 608 with the air/fuel ratio 464 to producethe sixth temperature contribution 604. As stated above, the air/fuelratio 464 may be expressed as an equivalence ratio value (e.g., targetair/fuel ratio relative to a stoichiometric air/fuel ratio). The sixthtemperature contribution 604 corresponds to heating (i.e., temperatureincrease relative to the ambient temperature 424) from the air/fuelmixture supplied to the engine.

An eighth component module 612 generates a seventh temperaturecontribution 616 (e.g., in degrees K, C, or F) based on the ECT 420, theambient temperature 424, and the IAT 428. The eighth component module612 generates the seventh temperature contribution 616 as a function ofthe ECT 420, the ambient temperature 424, and the IAT 428. The functionmay be, for example, a mapping or an equation including one or more ofthe predetermined values 416 that relates ECTs, ambient temperatures,and IATs to seventh temperature contributions. The seventh temperaturecontribution 616 corresponds to a radiation heat loss (i.e., temperaturedecrease toward the ambient temperature 424).

A first adder module 620 determines a temperature sum (u(n)) 624 (e.g.,in degrees K, C, or F) by summing the first, second, third, fourth,fifth, sixth, and seventh temperature contributions 512, 532, 548, 568,588, 604, and 616. A difference module 628 determines a firsttemperature change 632 (e.g., in degrees K, C, or F) by subtracting aprevious temperature difference 636 (e.g., in degrees K, C, or F) fromthe temperature sum 624. The previous temperature difference 636corresponds to a value of a temperature difference 640 from a lastcontrol loop, as discussed further below. A multiplier module 644multiplies the first temperature change 632 by a gain value 648 todetermine a second temperature change 652 (e.g., in degrees K, C, or F).

A gain module 656 determines the gain value 648 based on the ECT 420.For example the gain module 656 may determine the gain value 648 using amapping or an equation including one or more of the predetermined values416 that relates ECTs to gain values. The gain value 648 reflectsdynamic characteristics of the system and is related to the system'stime constant. While the example of the ECT 420 is used, the gain valuemay be determined based on one or more other measured parameters. Thefirst, second, third, fourth, fifth, sixth, seventh, and eighthcomponent modules 504, 524, 540, 556, 560, 580, 596, and 612, and thegain module 656 update their respective outputs once per predeterminedperiod, such as a predetermined period of time or a predetermined amountof crankshaft rotation.

A temperature difference module 660 determines the temperaturedifference 640 by summing the second temperature change 652 with theprevious temperature difference 636. The temperature difference 640corresponds to how much warmer the estimated temperature 408 is than areference temperature, such as the ambient temperature 424. A delaymodule 664 stores the temperature difference 640 for the predeterminedperiod when the temperature difference 640 is updated and outputs theprevious temperature difference 636. The delay module 664 may include oract as one-unit a first-in first-out (FIFO) buffer. The previoustemperature difference 636 is the temperature difference 640 from thepredetermined period earlier.

An estimating module 668 determines the estimated temperature 408 basedon the temperature difference 640 and the ambient temperature 424. Forexample, the estimating module 668 may set the estimated temperature 408equal to the sum of the temperature difference 640 and the ambienttemperature 424. While the example of using the ambient temperature 424as the reference temperature is provided, another suitable referencetemperature may be used.

FIG. 6 includes a functional block diagram of an example implementationof the estimation module 290 including the temperature estimation module404 and one or more other temperature estimation modules, such as asecond temperature estimation module 680 . . . and N-th temperatureestimation module 684. Each other temperature estimation moduledetermines a respective estimated temperature at a respective locationin the exhaust system. For example, the second temperature estimationmodule 680 determines the second estimated temperature 688, and the N-thtemperature estimation module 684 determines the N-th estimatedtemperature 692.

The other temperature estimation modules each include the modules of thetemperature estimation module 404 shown and discussed with respect toFIG. 5. The other temperature estimation modules determine therespective estimated temperatures based on the input parameters 412 andpredetermined values calibrated for determining the respective estimatedtemperatures. For example, the second temperature estimation module 680determines the second estimated temperature 688 based on the inputparameters 412 and second predetermined values 694 for determining thesecond estimated temperature 688. The N-th temperature estimation module684 determines the N-th estimated temperature 692 based on the inputparameters 412 and N-th predetermined values 696 for determining theN-th estimated temperature 692. The configuration of the temperatureestimation module 404 therefore allows the same estimation strategy andinput parameters to be used to estimate multiple different exhaustsystem temperatures. Only the respective predetermined values arecalibrated for estimating different exhaust system temperatures.

FIG. 7 is a flowchart depicting an example method of determining anestimated exhaust system temperature, such as the estimated temperature408. The example of FIG. 7 is illustrative of one control loop, and acontrol loop may be initiated each predetermined period. Similar oridentical functions may be performed concurrently to determine one ormore other estimated temperatures.

Control may begin with 702 where the temperature estimation module 404samples the input parameters 412. At 704, the first, second, third,fourth, fifth, sixth, and seventh temperature contributions 512, 532,548, 568, 588, 604, and 616, respectively, are determined. As discussedabove, the first component module 504 and the first multiplier module508 generate the first temperature contribution 512 based on the VS 432,the radiator fan speed 436, the RPM 440, the MAP 444, and thetemperature difference 516 between the ECT 420 and the ambienttemperature 424. The second component module 524 and the secondmultiplier module 528 generate the second temperature contribution 532based on the temperature difference 516 between the ECT 420 and theambient temperature 424, the RPM 440, the MAP 444, the spark timing 448,and the MAF 452. The third component module 540 and the third multipliermodule 544 generate the third temperature contribution 548 based on theRPM 440 and the MFF 456. The fourth component module 556, the fifthcomponent module 560, and the fourth multiplier module 564 generate thefourth temperature contribution 568 based on the RPM 440, the WG opening460, the ECT 420, and the MAP 444. The sixth component module 580 andthe fifth multiplier module 584 generate the fifth temperaturecontribution 588 based on the MAP 444, the temperature difference 516between the ECT 420 and the ambient temperature 424, and the sparktiming 448. The seventh component module 596 and the sixth multipliermodule 600 generate the sixth temperature contribution 604 based on theMAP 444, the temperature difference 516 between the ECT 420 and theambient temperature 424, and the air/fuel ratio 464 being supplied tothe engine. The eighth component module 612 generates the seventhtemperature contribution 616 based on the ECT 420, the ambienttemperature 424, and the IAT 428.

At 708, the first adder module 620 sums the first, second, third,fourth, fifth, sixth, and seventh temperature contributions 512, 532,548, 568, 588, 604, and 616, respectively, to determine the temperaturesum 624. At 712, the difference module 628 determines the firsttemperature change 632 by subtracting the previous temperaturedifference 636 from the temperature sum 624. More specifically, thedifference module 628 sets the first temperature change 632 equal to orbased on the temperature sum 624 minus the previous temperaturedifference 636.

The gain module 656 determines the gain value 648 based on the ECT 420at 716. The multiplier module 644 also multiplies the first temperaturechange 632 by the gain value 648 to determine the second temperaturechange 652 at 716. At 720, the temperature difference module 660determines the temperature difference 640 based on the secondtemperature change 652 and the previous temperature difference 636. Forexample, the temperature difference module 660 may set the temperaturedifference 640 based on or equal to the second temperature change plusthe previous temperature difference 636.

At 724, the estimating module 668 determines the estimated temperature408 based on the ambient temperature 424 and the temperature difference640. For example, the estimating module 668 may set the estimatedtemperature 408 equal to or based on a sum of the ambient temperature424 and the temperature difference 640. One or more engine operatingparameters may be adjusted based on the estimated temperature 408. Forexample, the fuel control module 332, the boost control module 340, thethrottle control module 316, the spark control module 324, and/or thephaser control module 337 may control fueling, boost of one or moreboost devices, throttle opening, spark timing, and/or intake and/orexhaust cam phasing, respectively, based on the estimated temperature408. At 728, the delay module 664 sets the previous temperaturedifference 636 equal to the temperature difference 640 for use duringthe next control loop.

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.Further, although each of the embodiments is described above as havingcertain features, any one or more of those features described withrespect to any embodiment of the disclosure can be implemented in and/orcombined with features of any of the other embodiments, even if thatcombination is not explicitly described. In other words, the describedembodiments are not mutually exclusive, and permutations of one or moreembodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example,between modules, circuit elements, semiconductor layers, etc.) aredescribed using various terms, including “connected,” “engaged,”“coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and“disposed.” Unless explicitly described as being “direct,” when arelationship between first and second elements is described in the abovedisclosure, that relationship can be a direct relationship where noother intervening elements are present between the first and secondelements, but can also be an indirect relationship where one or moreintervening elements are present (either spatially or functionally)between the first and second elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A OR BOR C), using a non-exclusive logical OR, and should not be construed tomean “at least one of A, at least one of B, and at least one of C.”

In this application, including the definitions below, the term “module”or the term “controller” may be replaced with the term “circuit.” Theterm “module” may refer to, be part of, or include: an ApplicationSpecific Integrated Circuit (ASIC); a digital, analog, or mixedanalog/digital discrete circuit; a digital, analog, or mixedanalog/digital integrated circuit; a combinational logic circuit; afield programmable gate array (FPGA); a processor circuit (shared,dedicated, or group) that executes code; a memory circuit (shared,dedicated, or group) that stores code executed by the processor circuit;other suitable hardware components that provide the describedfunctionality; or a combination of some or all of the above, such as ina system-on-chip.

The module may include one or more interface circuits. In some examples,the interface circuits may include wired or wireless interfaces that areconnected to a local area network (LAN), the Internet, a wide areanetwork (WAN), or combinations thereof. The functionality of any givenmodule of the present disclosure may be distributed among multiplemodules that are connected via interface circuits. For example, multiplemodules may allow load balancing. In a further example, a server (alsoknown as remote, or cloud) module may accomplish some functionality onbehalf of a client module.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes, datastructures, and/or objects. The term shared processor circuitencompasses a single processor circuit that executes some or all codefrom multiple modules. The term group processor circuit encompasses aprocessor circuit that, in combination with additional processorcircuits, executes some or all code from one or more modules. Referencesto multiple processor circuits encompass multiple processor circuits ondiscrete dies, multiple processor circuits on a single die, multiplecores of a single processor circuit, multiple threads of a singleprocessor circuit, or a combination of the above. The term shared memorycircuit encompasses a single memory circuit that stores some or all codefrom multiple modules. The term group memory circuit encompasses amemory circuit that, in combination with additional memories, storessome or all code from one or more modules.

The term memory circuit is a subset of the term computer-readablemedium. The term computer-readable medium, as used herein, does notencompass transitory electrical or electromagnetic signals propagatingthrough a medium (such as on a carrier wave); the term computer-readablemedium may therefore be considered tangible and non-transitory.Non-limiting examples of a non-transitory, tangible computer-readablemedium are nonvolatile memory circuits (such as a flash memory circuit,an erasable programmable read-only memory circuit, or a mask read-onlymemory circuit), volatile memory circuits (such as a static randomaccess memory circuit or a dynamic random access memory circuit),magnetic storage media (such as an analog or digital magnetic tape or ahard disk drive), and optical storage media (such as a CD, a DVD, or aBlu-ray Disc).

The apparatuses and methods described in this application may bepartially or fully implemented by a special purpose computer created byconfiguring a general purpose computer to execute one or more particularfunctions embodied in computer programs. The functional blocks,flowchart components, and other elements described above serve assoftware specifications, which can be translated into the computerprograms by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that arestored on at least one non-transitory, tangible computer-readablemedium. The computer programs may also include or rely on stored data.The computer programs may encompass a basic input/output system (BIOS)that interacts with hardware of the special purpose computer, devicedrivers that interact with particular devices of the special purposecomputer, one or more operating systems, user applications, backgroundservices, background applications, etc.

The computer programs may include: (i) descriptive text to be parsed,such as HTML (hypertext markup language) or XML (extensible markuplanguage), (ii) assembly code, (iii) object code generated from sourcecode by a compiler, (iv) source code for execution by an interpreter,(v) source code for compilation and execution by a just-in-timecompiler, etc. As examples only, source code may be written using syntaxfrom languages including C, C++, C#, Objective C, Haskell, Go, SQL, R,Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5,Ada, ASP (active server pages), PHP, Scala, Eiffel, Smalltalk, Erlang,Ruby, Flash®, Visual Basic®, Lua, and Python®.

None of the elements recited in the claims are intended to be ameans-plus-function element within the meaning of 35 U.S.C. §112(f)unless an element is expressly recited using the phrase “means for,” orin the case of a method claim using the phrases “operation for” or “stepfor.”

What is claimed is:
 1. A control system for an engine of a vehicle,comprising: an adder module that determines a temperature sum based on asum of a plurality of temperatures determined based on (i) a pluralityof operating parameters of the vehicle and (ii) a plurality ofpredetermined values calibrated for determining an estimated temperatureat a location within an exhaust system of the vehicle; a temperaturedifference module that determines a temperature difference based on thetemperature sum and a previous value of the temperature difference; anestimating module that determines the estimated temperature at thelocation within the exhaust system based on the temperature differenceand a reference temperature; and an actuator control module thatselectively adjusts at least one engine actuator based on the estimatedtemperature.
 2. The control system of claim 1 further comprising: afirst change module that determines a first temperature change based ona difference between the temperature sum and the previous value of thetemperature difference; and a second change module that determines asecond temperature change based on a product of the first temperaturechange and a gain value, wherein the temperature difference module setsthe temperature difference based on a sum of the previous value of thetemperature difference and the second temperature change.
 3. The controlsystem of claim 2 further comprising a gain module that determines thegain value based on an engine coolant temperature.
 4. The control systemof claim 1 wherein the estimating module determines the estimatedtemperature at the location within the exhaust system based on a sum ofthe temperature difference and the reference temperature.
 5. The controlsystem of claim 1 wherein the plurality of operating parameters includeat least two of: (i) a vehicle speed; (ii) a radiator fan speed; (iii)an engine speed; (iv) a manifold pressure; (v) an engine coolanttemperature; (vi) a difference between the engine coolant temperatureand an ambient air temperature; (vii) a spark timing of the engine;(viii) a mass air flowrate into the engine; (ix) a mass fuel flowrate tothe engine; (x) a wastegate opening; (xi) a present air/fuel ratio ofthe engine; (xii) an intake air temperature; and (xiii) the ambient airtemperature.
 6. The control system of claim 1 wherein the plurality ofoperating parameters include: (i) a vehicle speed; (ii) a radiator fanspeed; (iii) an engine speed; (iv) a manifold pressure; (v) an enginecoolant temperature; (vi) a difference between the engine coolanttemperature and an ambient air temperature; (vii) a spark timing of theengine; (viii) a mass air flowrate into the engine; (ix) a mass fuelflowrate to the engine; (x) a wastegate opening; (xi) a present air/fuelratio of the engine; (xii) an intake air temperature; and (xiii) theambient air temperature.
 7. The control system of claim 1 wherein theplurality of operating conditions do not include any temperaturemeasured in the exhaust system using a temperature sensor.
 8. Thecontrol system of claim 1 wherein the plurality of operating conditionsdo not include any pressure measured in the exhaust system using apressure sensor.
 9. The control system of claim 1 further comprising: asecond adder module that determines a second temperature sum based on asum of a second plurality of temperatures determined based on (i) theplurality of operating parameters of the vehicle and (ii) a secondplurality of predetermined values calibrated for determining a secondestimated temperature at a second location within the exhaust system ofthe vehicle; a second temperature difference module that determines asecond temperature difference based on the second temperature sum and aprevious value of the second temperature difference; and a secondestimating module that determines the second estimated temperature atthe second location within the exhaust system of the vehicle based onthe second temperature difference and the reference temperature, whereinthe actuator control module further selectively adjusts at least oneengine actuator based on the second estimated temperature.
 10. Thecontrol system of claim 1 wherein, based on the estimated temperature,the actuator control module selectively adjusts at least one of openingof a throttle valve, fueling of the engine, spark timing of the engine,cam phasing of the engine, opening of an exhaust gas recirculation (EGR)valve, and opening of a wastegate.
 11. A control method for an engine ofa vehicle, comprising: determining a temperature sum based on a sum of aplurality of temperatures determined based on (i) a plurality ofoperating parameters of the vehicle and (ii) a plurality ofpredetermined values calibrated for determining an estimated temperatureat a location within an exhaust system of the vehicle; determining atemperature difference based on the temperature sum and a previous valueof the temperature difference; determining the estimated temperature atthe location within the exhaust system based on the temperaturedifference and a reference temperature; and selectively adjusting atleast one engine actuator based on the estimated temperature.
 12. Thecontrol method of claim 11 further comprising: determining a firsttemperature change based on a difference between the temperature sum andthe previous value of the temperature difference; and determining asecond temperature change based on a product of the first temperaturechange and a gain value, wherein determining the temperature differenceincludes setting the temperature difference based on a sum of theprevious value of the temperature difference and the second temperaturechange.
 13. The control method of claim 12 further comprisingdetermining the gain value based on an engine coolant temperature. 14.The control method of claim 11 wherein determining the estimatedtemperature includes determining the estimated temperature at thelocation within the exhaust system based on a sum of the temperaturedifference and the reference temperature.
 15. The control method ofclaim 11 wherein the plurality of operating parameters include at leasttwo of: (i) a vehicle speed; (ii) a radiator fan speed; (iii) an enginespeed; (iv) a manifold pressure; (v) an engine coolant temperature; (vi)a difference between the engine coolant temperature and an ambient airtemperature; (vii) a spark timing of the engine; (viii) a mass airflowrate into the engine; (ix) a mass fuel flowrate to the engine; (x) awastegate opening; (xi) a present air/fuel ratio of the engine; (xii) anintake air temperature; and (xiii) the ambient air temperature.
 16. Thecontrol method of claim 11 wherein the plurality of operating parametersinclude: (i) a vehicle speed; (ii) a radiator fan speed; (iii) an enginespeed; (iv) a manifold pressure; (v) an engine coolant temperature; (vi)a difference between the engine coolant temperature and an ambient airtemperature; (vii) a spark timing of the engine; (viii) a mass airflowrate into the engine; (ix) a mass fuel flowrate to the engine; (x) awastegate opening; (xi) a present air/fuel ratio of the engine; (xii) anintake air temperature; and (xiii) the ambient air temperature.
 17. Thecontrol method of claim 11 wherein the plurality of operating conditionsdo not include any temperature measured in the exhaust system using atemperature sensor.
 18. The control method of claim 11 wherein theplurality of operating conditions do not include any pressure measuredin the exhaust system using a pressure sensor.
 19. The control method ofclaim 11 further comprising: determining a second temperature sum basedon a sum of a second plurality of temperatures determined based on (i)the plurality of operating parameters of the vehicle and (ii) a secondplurality of predetermined values calibrated for determining a secondestimated temperature at a second location within the exhaust system ofthe vehicle; determining a second temperature difference based on thesecond temperature sum and a previous value of the second temperaturedifference; determining the second estimated temperature at the secondlocation within the exhaust system of the vehicle based on the secondtemperature difference and the reference temperature; and selectivelyadjusting at least one engine actuator based on the second estimatedtemperature.
 20. The control method of claim 11 wherein adjusting atleast one engine actuator includes adjusting at least one of opening ofa throttle valve, fueling of the engine, spark timing of the engine, camphasing of the engine, opening of an exhaust gas recirculation (EGR)valve, and opening of a wastegate.